In recent years, implantable biomedical telemetry devices (implants) have gained much attention for a variety of applications including generating stimulus signals, monitoring the body, and communicating internal vital signs to the outer world. Providing power to these implants is one of the major challenges in designing such systems. Power requirements for implants vary with the application and can range from a few milliwatts to dozens of milliwatts or more. Some implants are battery operated and their application is limited due to the device size, weight, and battery longevity. For applications involving mice, battery size and weight is more problematic for long duration experiments (1 or more days). In some cases, implants use rechargeable batteries, where those systems employ wireless recharging.
A vast majority of the research on neural mechanisms of therapies is currently conducted using rodent models. Implantable biotelemetry systems are effective tools for clinical medicine and also in animal research, because they allow for the acquisition of otherwise unavailable physiological data, such as high quality internal electromyographic (EMG) data, electroencephalogy (EEG) data, motion data, or other data. High-quality data means many sample points per-unit-time, for a high fidelity waveform. For example, an EEG signal is considered acceptable quality with 200 samples/second at minimum, but ideally 2000 samples/second or higher.
Gathering high quality behavioral and biological data from small rodents is important for the study of various disease models in biomedical research. Acquisition of high quality data requires reasonable power for the electronics to sample at such rates, digitize the data, and then transmit it by radio signal. Presently, the largest permissible size/weight battery acceptable for mice would lose power in about 30 minutes if it had to acquire and transmit data at 200 samples/sec. The only way to perform high quality data sampling and transmission for continuous periods of several hours or longer is with a wireless power scheme. In addition, to conduct research with small animals effectively, they must be able to move freely inside their cage. However, the continuously changing orientation of the small animals leads to coupling loss/problems between the primary (transmitter) and secondary (receiver) coils, presenting a major challenge. Furthermore, excess power obtained by good orientation between the primary and secondary coils can include undesirable results, such as device malfunction and tissue damage. Thus, a need exists in the art for devices and systems capable of wireless power transmission for powering the performance requirements for telemetric devices for animal monitoring, including devices and systems that are suitable for monitoring multiple different animals in a single environment and that can control the level of power produced during use.